A circuit breaker is an overcurrent protective device that is used for circuit protection and isolation. The circuit breaker provides electrical system protection when a designated electrical abnormality such as an overcurrent or overload event occurs in the system. One type of circuit breaker is a miniature circuit breaker (MCB), which is typically used for low voltage applications. An MCB typically includes a base and cover, and an electrical circuit between a line terminal and a load terminal. The electrical circuit includes a conductive stationary contact electrically connected to one of the terminals and a movable contact electrically connected to the other terminal. The movable contact is secured on a movable blade (also referred to as a contact carrier). A handle interfaces with the blade and the trip lever of the trip mechanism as further explained below. The handle can be operated by a user to move the blade, and thus the movable contact, between an open position and a closed position to open or close the electrical circuit. In the closed position, the movable contact is engaged with the stationary contact to allow current flow between the two contacts to a protected load. In the open position, the movable contact is disengaged from the stationary contact to prevent or interrupt current flow to the protected load.
The MCB also includes a trip mechanism. The trip mechanism controls a trip lever, which is connected to the blade via a tension spring (also known as a “toggle spring”). When an abnormal operating condition is detected (e.g., an over current or over temperature fault), the trip mechanism implements a trip operation to disengage the movable contact from the stationary contact by releasing or unlatching the trip lever, which in turn interrupts current flow to the protected load at another open position generally referred to as the tripped position. The handle is also moved to the tripped position. Thereafter, the circuit breaker can be returned to an open position. Once in the open position, the user can move the breaker back to the closed position via the handle. The handle position provides a user with the operational status of the MCB; however, the user must visually inspect the circuit breaker to observe its status. Thus, the user may be unaware of the operational status of a particular circuit breaker, particularly when it is tripped or is not operating properly. Furthermore, there are significant design restrictions when incorporating additional status monitoring components into a circuit breaker. For example, a circuit breaker, such as a MCB, is subject to size constraints.